... I do think the equivalent of a quack is more likely to go unexposed outside of the collective knowledge bases.
I'm not sure I'd agree with this. What I have found is that within a certain community (including the majority of people who practice aikido as part of a major organization, as many people on this and other aikido forums do), those who are not part of a major organization are immediately suspect and it is often considered acceptable to insult and ridicule them for their offenses, whether perceived or real. On the other hand, people who are part of a major organization, and especially those who are higher up in such organizations, are automatically considered legitimate and are usually afforded the benefit of the doubt. Instead of subjecting them to criticism, any errors that they appear to be making are rationalized in various ways to make those errors seem unimportant or irrelevant, and those who do dare to engage in any criticism of them are the ones more likely to be attacked for being "disrespectful".
Because of this tendency to assume that qualifications from a major organization are beyond question, these organizations often enable people of lesser skill who have managed to climb the political ladder to maintain a veneer of respectability based on the illusion that they have a lot more skill than they do. In my opinion, this starts at the highest level in the aikikai (which is a good example since it is the biggest and most widely recognized organization) and is a widespread problem there. The overly-compliant style of ukemi used in that and many other aikido organizations allows this practice to continue without the majority of the students noticing what is going on. They are told, explicitly or implicitly, never to challenge the teacher, and many never think to ask why because they just assume or are told that this is the "traditional" way and that this is how things should or must be in a dojo (never mind that in any number of other arts this is not the case).
Because martial arts organizations do not have rigorous, independently verified, competitively administered, objective standards as professional organizations do, such people never have to be challenged on their lack of skill by those outside of their own dojo or organization either. As long as they manage to keep the one or two people in charge of issuing their credentials happy, they can have the backing of a major, well-respected (in certain circles, at least) organization and can avoid having their skills tested in any meaningful way. It's not hard to see how such a system is inherently prone to corruption and thus would be considered wholly inadequate for any professional or any other kind of organization where failing to maintaining a certain level of quality could have real consequences.
If you want to respect the rank that comes from major aikido organizations, as many people here and elsewhere do, that's up to you. Organizations are not inherently bad and they have done a lot to contribute to the art, although they do have a tendency to take on a life of their own and advance their own goals at the expense of those of their membership. Usually in a big organization you are assured of at least a certain typically mediocre level of quality, and while there are a few outstanding people, the excellent people who stay in the organizations tend to be pulled down towards the norm and are often prevented from exploring new avenues of discovery that could take them away from or beyond what other people in their group are doing. This is especially true in the big groups with large, established hierarchies and this trend will likely continue as their styles become more standardized. On the other hand, those of truly no talent usually do not end up in positions of power in major organizations, as they often do in the soke-dokey groups. So if you are happy with mediocre and don't have the ability to recognize total crap when you see it, then an organization is a safe choice. If you want the best, you will have to evaluate individuals for yourself, and you might be just as likely, if not more so, to find what you want outside of an organization as inside one.